State-of-art scalable hierarchical coding methods allow to encode the information hierarchically in order that it can be decoded at different resolution and/or quality levels. A data stream generated by a scalable coding device is thus divided into several layers, a base layer and one or more enhancement layers, also called high layers. These devices allow to adapt a unique data stream to variable transmission conditions (bandwidth, error rate . . . ) and also to the capacities of reception devices (CPU, characteristics of reproduction device . . . ). A spatially scalable hierarchical encoding method encodes (or decodes) a first part of data called base layer relating to low resolution pictures, and from this base layer encodes (or decodes) at least another data part called enhancement layer relating to high resolution pictures. The coding information relating to enhancement layer are possibly inherited (i.e. derived) from coding information relating to the base layer by a method called inter-layer prediction method. The derived coding information may possibly comprise: a partitioning pattern associated with block of pixels of the high resolution picture (for splitting said block into several sub-blocks), coding modes associated with said blocks, possibly motion vectors and one or more picture reference indices associated with some blocks allowing to reference the picture used to predict said block. A reference picture is an picture of the sequence used to predict another picture of the sequence. Thus, if not explicitly coded in the data stream, the coding information relating to the enhancement layer has to be derived from the coding information relating to low resolution pictures. State-of-art methods for deriving coding information cannot be used for high resolution pictures whose format is not linked to the format of low resolution pictures by a dyadic transform.